Aptamer-Based\nElectrochemical Biosensing Platform\nfor Analysis of Cardiac Biomarkers

Monitoring\nbiomarkers secreted by cardiomyocytes is critical\nto\nevaluate anticancer drug-induced myocardial injury (MI). Cardiac troponin\nI (cTnI) is considered the gold standard biomarker for MI. Herein,\nan electrochemical aptasensor is engineered for cTnI detection based\non lanthanide europium metal–organic frameworks (Eu-MOFs) and\na hybridization chain reaction-directed DNAzyme strategy. Three types\nof Eu-MOF morphologies were easily synthesized by changing the solvent,\nand the Eu-MOF modulated by mixing the solvent of dimethylformamide\nand H<sub>2</sub>O (D-Eu-MOF) exhibited the best performance compared\nto other morphologies of the Eu-MOFs. Multifunctional nanoprobes were\nconstructed from D-Eu-MOF@Pt loaded with natural horseradish peroxidase\nand combined with an aptamer-initiated nuclear acid hybridization\nchain reaction to form G-quadruplex/hemin DNAzymes for signal amplification.\nA novel capture probe is constructed on the basis of DNA nanotetrahedrons\nmodified on screen-printed gold electrodes to enhance the capture\nof the target and multifunctional nanoprobes for signal amplification.\nIt exhibits a detection limit of 0.17 pg mL<sup>–1</sup> and\na linear range from 0.5 pg mL<sup>–1</sup> to 15 ng mL<sup>–1</sup>. The practicality of the platform is evaluated by\nmeasuring cTnI in real samples and secreted by cardiomyocytes after\ndrug treatment, which provides great potential in drug-induced MI\nevaluation for clinical application.